from calendar import month_name

from django.contrib.auth import get_user_model
from django.http import Http404
from django.shortcuts import get_object_or_404
from django.template.response import TemplateResponse
from django.utils.translation import ugettext_lazy as _

from mezzanine.blog.models import BlogPost, BlogCategory
from mezzanine.blog.feeds import PostsRSS, PostsAtom
from mezzanine.conf import settings
from mezzanine.generic.models import Keyword
from mezzanine.utils.views import paginate

User = get_user_model()


def blog_post_list(
    request,
    tag=None,
    year=None,
    month=None,
    username=None,
    category=None,
    template="blog/blog_post_list.html",
    extra_context=None,
):
    """
    Display a list of blog posts that are filtered by tag, year, month,
    author or category. Custom templates are checked for using the name
    ``blog/blog_post_list_XXX.html`` where ``XXX`` is either the
    category slug or author's username if given.
    """
    templates = []
    blog_posts = BlogPost.objects.published(for_user=request.user)
    if tag is not None:
        tag = get_object_or_404(Keyword, slug=tag)
        blog_posts = blog_posts.filter(keywords__keyword=tag)
    if year is not None:
        blog_posts = blog_posts.filter(publish_date__year=year)
        if month is not None:
            blog_posts = blog_posts.filter(publish_date__month=month)
            try:
                month = _(month_name[int(month)])
            except IndexError:
                raise Http404()
    if category is not None:
        category = get_object_or_404(BlogCategory, slug=category)
        blog_posts = blog_posts.filter(categories=category)
        templates.append(u"blog/blog_post_list_%s.html" % str(category.slug))
    author = None
    if username is not None:
        author = get_object_or_404(User, username=username)
        blog_posts = blog_posts.filter(user=author)
        templates.append(u"blog/blog_post_list_%s.html" % username)

    prefetch = ("categories", "keywords__keyword")
    blog_posts = blog_posts.select_related("user").prefetch_related(*prefetch)
    blog_posts = paginate(
        blog_posts,
        request.GET.get("page", 1),
        settings.BLOG_POST_PER_PAGE,
        settings.MAX_PAGING_LINKS,
    )
    context = {
        "blog_posts": blog_posts,
        "year": year,
        "month": month,
        "tag": tag,
        "category": category,
        "author": author,
    }
    context.update(extra_context or {})
    templates.append(template)
    return TemplateResponse(request, templates, context)


def blog_post_detail(
    request,
    slug,
    year=None,
    month=None,
    day=None,
    template="blog/blog_post_detail.html",
    extra_context=None,
):
    """. Custom templates are checked for using the name
    ``blog/blog_post_detail_XXX.html`` where ``XXX`` is the blog
    posts's slug.
    """
    blog_posts = BlogPost.objects.published(for_user=request.user).select_related()
    blog_post = get_object_or_404(blog_posts, slug=slug)
    related_posts = blog_post.related_posts.published(for_user=request.user)
    context = {
        "blog_post": blog_post,
        "editable_obj": blog_post,
        "related_posts": related_posts,
    }
    context.update(extra_context or {})
    templates = [u"blog/blog_post_detail_%s.html" % str(slug), template]
    return TemplateResponse(request, templates, context)


def blog_post_feed(request, format, **kwargs):
    """
    Blog posts feeds - maps format to the correct feed view.
    """
    try:
        return {"rss": PostsRSS, "atom": PostsAtom}[format](**kwargs)(request)
    except KeyError:
        raise Http404()
